Radio controlled safety stop system for forklift trucks with rfid

ABSTRACT

A security system including an RFID subsystem for detecting entry of an RFID tag within a monitored area; an RFID token associated with a person accessing the monitored area; and an indicator system for providing an indication when the person enters into the monitored area.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 12/171,075(now U.S. Pat. No. 8,314,686) filed 10 Jul. 2008 that in turn claimsbenefit of provisional patent application 61/059,262 filed 5 Jun. 2008entitled RADIO CONTROLLED SAFETY STOP SYSTEM FOR FORKLIFT TRUCKS WITHRFID, the entireties of their contents are hereby expressly incorporatedby reference thereto for all purposes. This application is related toU.S. Pat. No. 4,849,735 issued 18 Jul. 1989 and titled RADIO CONTROLLEDSAFETY STOP SYSTEM FOR FORKLIFT TRUCKS WITH RFID.

BACKGROUND OF THE INVENTION

This invention relates to safety systems, and more particularly to asafety system applicable to a forklift truck to prevent the forklifttruck from inadvertently causing injury of personnel on loading docks,warehouses, and other locations where forklift trucks are operated nearpeople.

This invention is an improvement to U.S. Pat. No. 4,849,735 titled“Radio controlled safety stop system for forklift trucks” issued 18 Jul.1989 and assigned to the present inventor. A search of the prior artrelated to U.S. Pat. No. 4,849,735 was made, has revealed the existenceof U.S. Pat. Nos. as follows: 4,079,802; 2,804,160; 3,683,379;3,898,652; 4,528,563; 3,892,483; 3,976,151; 4,278,962; 4,136,329; and3,882,957.

Referring to each of the patents in the order in which they were issued,U.S. Pat. No. 2,804,160 discloses a concept of controlling a trailingvehicle so that it does not rear-end a vehicle in front of it. Itaccomplishes this purpose by transmitting a radio signal that isreflected from the leading vehicle and is received by the trailingvehicle. The received signal initiates actuation of the brakes or theignition system of the trailing vehicle so as to prevent a collision.

U.S. Pat. No. 3,683,379 discloses an invention similar to U.S. Pat. No.2,804,160, but it does so in a different way and with a differentcircuitry. In this patent, one of the head lamps of the vehicle is usedas both the transmitter (filament) and the receiver (reflector) of thereflected wave of radio frequency energy that is reflected from theleading car. The signal so received is then used to actuate an alarm towarn the driver, or to actuate a brake operating solenoid to effectdeceleration of the vehicle as required.

U.S. Pat. No. 3,882,957 discloses the concept of a “tilt” switch for usewith automobiles so that the ignition and fuel supply are shut off itthe vehicle tilts beyond a certain degree. Obviously, this patent has nosignificant relevance with regard to preventing a forklift truck fromrunning into a closed door.

U.S. Pat. No. 3,892,483 discloses the concept of transmitting a signalboth forwardly and backwardly so as to alert motorists in front andbehind the vehicle transmitting the signal of their proximity inrelation to the vehicle transmitting the signal. Remedial action isinitiated by the vehicle, in front or in back, which receives thesignal. One of the difficulties encountered with this disclosure is thatit presumes that all vehicles in a line of vehicles are similarlyequipped, and that there will be interaction between the signalstransmitted by the vehicles, i.e., the forwardly transmitted signal of atrailing vehicle will interact with the rearwardly transmitted signal ofa leading vehicle. Obviously, such a state of affairs could not bemandated unless required by law.

This application also discloses the concept of a radio signaltransmitted rearwardly, the signal varying in intensity (reduced) atincreasing distances from the rear of the vehicle. Conceptually, when atrailing vehicle, having an appropriate receiver, enters the radiationarea or zone created by the transmitter on the leading vehicle, thereceiver on the trailing vehicle initiates a controlling function, i.e.,actuates a buzzer, a light or actuates application of the brakes, orinterruption of the ignition system.

U.S. Pat. No. 3,898,652 discloses an even more elaborate system than theone immediately preceding in that it discloses the use of side sensorsin addition to the use of front and rear sensors. The sensors sense thelocation of surrounding vehicles, and channel this information into asignal processing unit. The velocity of the vehicle is also sensed, andfed into the processor, which then calculates whether the vehicle canstop in time to avoid running into any other vehicles. The output of theprocessor may be applied to the vehicle brake and accelerator controlsfor slowing down a vehicle if the operator does not respond promptly toa warning signal.

U.S. Pat. No. 3,976,151 discloses a system for enabling a golf cart tofollow you around the golf course. A small transmitter carried by thegolfer transmits a radio frequency signal that is coupled magneticallywith a directional antenna on the cart. The cart also carries guidancedevices to control the power applied to the wheels so as to make thecart follow the golfer in response to the direction from which thesignal emanates.

U.S. Pat. No. 4,079,802 discloses circuitry for controlling the distancebetween two vehicles traveling at varying velocities. It accomplishesthis purpose by sensing the velocity of the trailing vehicle, sensingthe velocity of the leading vehicle, determining the difference in theirvelocities, and then uses this differential to determine what type ofcontrol to apply to the trailing vehicle to maintain a predeterminedminimum space between the vehicles. It is interesting to note that thecircuitry will not only decelerate the trailing vehicle when necessary,but will also accelerate it to maintain the predetermined spacingbetween the vehicles.

U.S. Pat. No. 4,136,329 discloses a control of the engine of a largetruck, such as a large diesel engine. The device monitors certainparameters that must fall within a predetermined range. If theparameters fall outside that range, the control device first warns ofthe danger, then initiates action to shut down the engine if the driverdoes not respond. The driver is provided with means for overriding thesystem when necessary of advisable.

U.S. Pat. No. 4,278,962, discloses an automatic alarm system fordetecting obstacles, such as walls or doors, behind a vehicle that isproceeding in reverse. Structurally, a transmitter and a receiver aremounted on a rotating disk contained within a housing mounted on thevehicle. An aperture in the housing permits transmission of a supersonicsignal which is reflected from any obstructions and re-enters the hole,or aperture, to be picked up by the receiver. The received signalinitiates an alarm, warning the driver that he is approaching anobstacle.

U.S. Pat. No. 4,528,563 discloses a concept that utilizes sound and thefrequency of an intermittent sound to alert a driver that he isapproaching an obstruction. The sound emanates from different areas,left front, left rear, right front, or right rear, to alert the driverof the direction of the obstruction. This device is said to beparticularly adapted to warn the driver when he is backing his vehicle,such as when backing into a garage where his visibility is limited.

We have found that many manufacturing plants and warehouses utilize vastsquare footage areas to perform their various functions, and thatdelivery of supplies and the shipping of materials from these plants isfrequently by truck or railroad car. To facilitate receiving andshipping goods from these plants, it is the practice to provide shippingand receiving ramps that are elevated above grade level so as toapproximate the height of the bed of a truck backed up to the ramp.Alternatively, where railroad cars are used to receive and ship goods atthese plants, the ramp is usually spaced from the open door of therailroad car by approximately 3 or 4 feet, and a heavy steel plate orapron is extended between the building ramp and the railroad car to fillthe gap and permit the transfer or reception of goods between therailroad car and the plant. In most of these instances, reception ofgoods and supplies by the plant, or shipment of manufactured goods fromthe plant or warehouse, is done through large openings in various wallsof the plant building that provide an unobstructed opening through whichforklift trucks may move. Thus, forklift trucks, under the control of anoperator, move back and forth through the opening between the bed of aflat bed truck backed up to the loading ramp, or into the boxcar fromwhich goods are being off-loaded, or into which goods are being loadedfor shipment.

It is the custom in industry to utilize large roll-up doors for closingand opening the doorways through which products move. These roll-updoors are frequently articulated steel doors, rolled up by anappropriate motor energized by a worker when the need arises to open orclose the door. One of the problems that has plagued industry is thatforklift truck operators, for whatever reason, frequently run into thesedoors with their forklift trucks when the doors are in a closedposition. Accordingly, one of the important objects of this invention isthe provision of a system that will prevent a forklift operator fromdriving his forklift truck into a closed door.

The incidence of damage to plant and warehouse doors by the ramming ofsuch doors with a forklift truck has become almost endemic. Severaloverhead door companies maintain several crews busy repairing suchdamage. At today's labor and material costs, the repair of such doorscan frequently amount to several times the cost of a device such as theone forming the subject matter of this invention for preventing thedamage. But the damage to the door cannot be measured only in terms oftime and material to effect the repair. Additionally, the doorway inwhich a damaged door is mounted is out of service for whatever length oftime it requires a door repair company to effect the repairs. Sometimesthis can be many days, even weeks, while vital parts that are notreadily available locally are ordered from the factory and received andinstalled. Sometimes, the factory sends the wrong part, even though itwas properly ordered, thus prolonging the time that the doorway is outof order and unusable by the plant or warehouse. In a case where thedoor that has been damaged happens to be the only door into or out ofthe premise for goods being received or shipped, it sometimes becomesnecessary to disassemble the entire door assembly and leave itdisassembled until either a new door or a repaired door can beinstalled, with the interval being covered from a security standpoint bythe hiring of special security personnel. Again, the cost inherent inthe repair of the door far outweighs the cost of a safety device toprevent the damage in the first place.

Besides the risk to the physical premises, other serious concernsinclude safety of personnel in the area where the forklift trucks areoperated as well as concern about authorized access to the area andgoods in these areas both from a theft as well as tampering concerns. Itis not uncommon for these systems to employ several independent forklifttrucks each loading/unloading one or more transportation vehicles. Theoperators of these forklift trucks are trying to be efficient and drivewith significant speed. Other personnel may share this area, and areoften on foot while they move in this area as well, checking status ofthe various operational parameters in the business. The environment isusually loud and visibility may be impaired. This is especially true asa forklift operator as a forklift truck operator must enter into theactual truck or railroad car, sometimes with a full load. As people maybe in the area as well, there is a very real risk of injury.

Additionally, these large areas may store significant quantities ofgoods for distribution to the public. Besides the risk of theft of thesegoods, maintaining security of the various areas is important to reducerisk of tampering with the goods. The Department of Homeland Securityhas increased requirements for area security for areas that warehousevolumes of such disposable goods (particularly food and chemicals).

Accordingly, another important object of the invention is the provisionof a radio controlled safety stop system for forklift trucks that willalert the driver that he is approaching a danger zone when the forklifttruck is a predetermined distance from the door or other controlled areathat includes a person, and which automatically interrupts the ignitionsystem of the forklift truck to thereby stop the forklift truck when theforklift truck operator ignores the warning system and continues movingin the direction of danger.

While emphasis has been placed above on the need for a safety device forforklift trucks to prevent the forklift truck from ramming and therebydamaging a closed roll-up overhead door, it is of equal importance thata forklift truck be precluded from driving through an open door underconditions which are unsafe, such as when a truck or a railroad car isnot parked adjacent to the platform, thus causing the forklift truck,with its load and operator to drive off the loading platform, withattendant damage to the forklift truck, its cargo and injury to thedriver. Accordingly, a still further object of the present invention isthe provision of a radio control safety stop system for forklift trucksthat will operate to stop a forklift truck from passing through even anopen doorway when unsafe conditions prevail.

Forklift trucks that are used in the industrial arena are frequentlyvery heavy vehicles. Some of these forklift trucks weigh as much as 4and 5 thousand pounds. It is believed that forklift trucks designed foruse within a building such as a warehouse or manufacturing plant aregeared to travel at perhaps no more than 5 miles per hour. Obviously,there are some exceptions. However, even at 5 miles per hour, a heavilyloaded forklift truck can impose a terribly destructive force if itimpacts an obstacle, such as a closed door. Since it appears to beimpractical to initially stop the forklift truck when it comes within apredetermined distance of the doorway, it is one of the objects of thisinvention to initially sound an alarm so that the operator of theforklift truck may himself take remedial action to stop the forklifttruck.

It is another object of the invention to only secondarily take controlof the forklift truck out of the hands of the human operator and tointerrupt the ignition system of the forklift truck when the forklifttruck is within a predetermined proximity to the door.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing will be apparent from the followingdescription and the drawings. It is to be understood however that theinvention is not limited to the embodiment illustrated and describedsince it may be embodied in various forms within the scope of theappended claims.

BRIEF SUMMARY OF THE INVENTION

One purpose of this safety equipment is to prevent forklifts fromcausing injury and deaths of personnel on loading docks and inwarehouses. It will also be used on the outside of the perimeter,wherever people and forklifts would come into contact. In the event thatthey come too close it will cause the forklift to shut down. The presentinvention includes apparatus, system, and method. The system includes anRFID subsystem for detecting entry of an RFID tag within a monitoredarea; an RFID token associated with a person accessing the monitoredarea; and an indicator system for providing an indication when theperson enters into the monitored area.

There will be RFID tags installed in hard hats and people will berequired to wear hard hats and vests and check in before going onto theproperty of the company. This will identify each person that is on thesight. In case of an emergency the identity of each person will betransferred to a computer as they checked in and the company will knowwho is on the premises.

In terms of broad inclusion, the radio control safety stop system forforklift trucks forming the subject matter of this invention comprises atransmitter mounted above a doorway in such a way that a radio signal iscontinuously transmitted by the transmitter in a pattern such that thesignal strength of the radio signal at a predetermined far distance fromthe door is detectably weaker than the radio signal that is detected ata predetermined near distance from the door. Mounted on the forklifttruck and provided with an appropriate antenna to detect the signalsbeing transmitted, is a radio receiver which detects the radio signalwhen the forklift truck moves into the far distance zone included by therelatively weak radio signal, and which then functions to actuate analarm to warn the driver that the is approaching a danger zone. If thedriver disregards the alarm and proceeds closer to the point of danger,say to the predetermined near distance limit at which the radio signalisomer intense, the radio receiver on the forklift truck detects thissecond level of radio signal strength and responds by actuating meanswhich disables the ignition system of the forklift truck, thus causingthe forklift truck to stop within a very short distance and certainlybefore it reaches the closed door, or the open doorway. We have foundthat for most installations, a far distance limit set at fifteen feetprovides sufficient time for the operator, if he is alert and aware ofthe danger, to take remedial action to stop the forklift truck.Additionally, we have found that if the forklift truck proceeds towithin about 4 feet from the closed door or open doorway, interruptingthe electrical ignition system at this point gives adequate opportunityto stop the forklift truck before it rams the closed door or passesthrough the open doorway. Since it frequently is necessary for theforklift truck to intentionally pass through an open doorway, means areproviding for disabling the transmitter when safe conditions prevail atthe doorway. In another aspect of the invention, it may be necessary fordifferent reasons to maintain an overhead door open during regularbusiness hours even if no truck or railroad car is present adjacent theloading platform. Under these circumstances, means are provided toactivate the radio control safety stop system for forklift trucks sothat a forklift truck driver, being preoccupied with other matters, willnot drive through an open doorway and off of the elevated loading ramp.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial view illustrating the environment and relationshipof the invention in its position of use;

FIG. 2 is a block diagram of the transmitter assembly;

FIG. 3 is a block diagram of the receiver assembly;

FIG. 4(A) is a schematic view of a portion of the receiver circuitry;

FIG. 4(B) is a continuation from 4(A) of the receiver circuitry;

FIG. 5 is a schematic view of the transmitter circuit;

FIG. 6 is an executive summary of an embodiment of the presentinvention;

FIG. 7 is an overview of featured product technology; and

FIG. 8 is a block schematic diagram of an alternate preferred embodimentof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to systems, and methods that reduces apotential of collision between a vehicle and a pedestrian by providingthe pedestrian with an RFID tag that is detectable, when in a desiredsafety range, by an operator of the vehicle (or the vehicle itself whenan automated vehicle/unattended vehicle) to first issue a warning withina first range and then to disable the vehicle when within a secondcloser range. The following description is presented to enable one ofordinary skill in the art to make and use the invention and is providedin the context of a patent application and its requirements. Variousmodifications to the preferred embodiment and the generic principles andfeatures described herein will be readily apparent to those skilled inthe art. Thus, the present invention is not intended to be limited tothe embodiment shown but is to be accorded the widest scope consistentwith the principles and features described herein.

One purpose of this safety equipment is to prevent forklifts fromcausing injury and deaths of personnel on loading docks and inwarehouses. It will also be used on the outside of the perimeter,wherever people and forklifts would come into contact. In the event thatthey come too close it will cause the forklift to shut down.

There will be RFID tags installed in hard hats and people will berequired to wear hard hats and vests and check in before going onto theproperty of the company. This will identify each person that is on thesight. In case of an emergency the identity of each person will betransferred to a computer as they checked in and the company will knowwho is on the premises.

Referring to FIG. 1, it will there be seen that the radio controlledsafety stop system for forklift trucks forming the subject matter ofthis invention is utilized in an area, such as a warehouse ormanufacturing plant in which a wall 2 is provided with a roll-up typedoor assembly designated generally by the numeral 3 and which includes afloor plate 4 and a roll-up mechanism 6 adapted to be activated in theconventional manner either manually by a chain working over a sprocketto effect roll-up of the door 7, or through use of an electric motordrive connected to the sprocket or to an appropriate gear drive wherebythe door 7 is rolled upwardly into an open position, or rolleddownwardly into a closed position by selective energization of theelectric motor. These controls are conventional and are therefore notillustrated in the drawing in the interest of brevity in thisdescription. Suffice to say that the door 7 is provided with means forde-energizing the electric motor when the door has reached either itsextreme open position or its extreme closed position. Such means forde-energizing the electric motor may be a switch of the type that isactuated by proximity to a magnetic which is supported on the door tobring it into proximity with the switch, or it may constitute a leverthat is abutted by an appropriate projection on the door, or it may beany of a number of other devices that may be used to interrupt power tothe electric motor.

Mounted on the wall 2 above the door, preferably medianly placedthereabove between the two side edges of the doorway, is a transmitterdesignated generally by the numeral 8, having a transmitting antenna 9projecting therefrom and adapted to transmit a very short range 360degree radio signal 12 that forms a radio signal “envelope” on theinterior and exterior of the building wall 2. The radio signal“envelope” must therefore be penetrated in order to reach the door 7.The radio signal 12is such that a pre-determined far distance D(1) fromthe door 7, the signal strength is relatively weak (level A) incomparison with the signal strength (level B) at pre-determined neardistance D(2) from the door. Stated another way, as the “envelope”formed by the radio signal is penetrated in a direction from the fardistance limit at which it is first detected toward the door meant to beprotected, the signal strength increases from a weak level A signal to asignificantly stronger level B signal. The difference in strength of theradio signal between level A and level B is sufficient to be detected,as will hereinafter be explained.

As illustrated in FIG. 1, the installation of the transmitter and thestrength of the radio signal 12 is “tailored” or “customized to bedetected and received by an antenna 13 appropriately connected to areceiver 14 mounted on the forklift truck 16. Preferably, the radiosignal 12 is adapted to be first detected by the receiving antenna 13 atfar distance D(1) when the tips of the tines or forks 17 of the forklift truck are approximately 15 feet away from the door. Obviously,because forklift trucks differ in their size, elevation and speed oftravel, and because antennas must be mounted on such forklift trucks indifferent locations, these dimensions may be varied to “customize” thesystem to a particular customer. Since, with the present system, it isdesirable that the ends of the forks of the forklift truck come nocloser than about 4 feet from the door, it will be seen from FIG. 1 thatthe antenna 13 will have been transposed to the near distance positionD(2) illustrated in broken lines when the ends of the tines or forks 17have reached the position where the forklift truck will be stopped toprevent it from damaging the door.

In the preferred embodiment, the door is equipped with an appropriatemagnet which comes into close proximity to a reed type switch (ON orOFF) responsive to the magnetic field of the magnet when the door is inopen position. When the door is in open position, the transmitter 8 isturned OFF by closing of the reed switch by the magnetic field of themagnet. When the door is closed, the magnet is far removed from the reedswitch and the switch is in its OFF position, and the transmitter isturned ON. Since this type of arrangement is conventional, and may varywith each installation because of local needs, it is omitted from thedrawings in the interest of clarity. Obviously, the reverse situationmay be arranged so that the transmitter is ON when the door is open.

The receiver 14 is energized whenever the ignition switch (not shown) ofthe forklift truck is ON to enable operation of the forklift truck. Onceenergized, the receiver “listens” for the coded signal from thetransmitter 8, which is coded in a manner to be hereinafter explained.When the receiver “hears” the correct coded radio signal, the alarmcircuitry and the ignition “kill” circuitry are “enabled” to respondwhen the forklift truck reaches the far distance D(1) position and thenear distance D(2) position, respectively. Thus, when the forklift truckis within about fifteen feet of the door, the alarm sounds, warning thedriver to take remedial action. If no remedial action is taken, and theforklift truck progresses to about four feet from the door, the ignitionof the forklift truck is interrupted and the forklift truck comes to astop before it can impact with and damage the door. Since leaving theforklift truck at the position at which the ignition was interruptedcould contribute to an unsafe situation, the system is provided with amomentary over-ride switch that can be manipulated by the operator tomove the forklift truck out of the restricted area.

Referring to the block diagram of FIG. 2, it will be seen that theproperly encoded signal is passed from the data encoder 21 through alow-pass filter 22 which conditions the signal and passes it on to theoscillator/FM modulator 23 which outputs a 53 MHz signal that ismultiplied by six at 24 to direct a 318 MHz signal into the amplifier26, and thence into the transmitter antenna 9. It will of course beunderstood that the transmitter is powered via a power cord plugged intoa standard 120 VAC power outlet commonly found in most buildings. Theseelements, being conventional, are shown schematically in the drawing inthe interest of clarity.

Referring to the receiver circuit illustrated in block diagram form inFIG. 3, the 318 MHz encoded signal is received by the antenna 13 on theforklift truck, passes through bandpass filter 27 and tuned amplifier 28and into the mixer 29. Local oscillator 31 feeds a 307.3 MHz signal intothe mixer 29, and the differential frequency of 10.7 MHz is fed throughamplifier 32, bandpass filter 33, amplifier 34, bandpass filter 36 to FMdemodulator 37. From the demodulator 37, the signal is passed to a datadecoder 38 on the one hand, and to a pair of signal level detectordevices 39 and 41 on the other hand. Valid data is channeled to a pairof AND gates 42 and 43 from the data decoder, and level A signalstrength detector 39 outputs to AND gate 42, while level B signalstrength detector 41 outputs to AND gate 43, whereupon buzzer 44 istriggered to sound when the forklift truck has reached the far distanceD(1) signal penetration position, and the ignition “kill” relay 46 isactivated when the forklift truck has reached the near distance signalpenetration limit illustrated in FIG. 1 of the drawing as D(2).

Transmitter

Referring with greater specificity to the transmitter circuitryillustrated schematically in FIG. 5, the transmitter is powered by powercord 51 adapted to plug into a conventional 120 VAC power outlet. Asillustrated, the primary winding of center-tap transformer 52 isprotected by a 0.5 amp fuse 53. The secondary winding of the transformeris connected as shown to a full wave rectifier bridge 54 of the typemanufactured and sold by Motorola under the trade designation 1N4001.Capacitors 56 and 57 filter the input voltage to the regulator 48, whichis conveniently of the LM7812 type manufactured by NationalSemiconductor. It should be noted that the LM78XX series of voltageregulators from National Semiconductor are functionally equivalent tothe MC7800 series voltage regulators manufactured and sold by Motorola.As shown, the output from the voltage regulator 58 is further filteredby capacitors 59 and 61.

Mounted on or in close proximity to the transmitter 8 is a reed-typeswitch (not shown) which is normally open when the door 7 is closed, butwhich responds to an appropriate magnet (not shown) mounted on the doorwhen the magnet is brought into close proximity to the reed switch bythe act of opening the door 7 to provide a passageway through the wall2. The effect of bringing the magnet into close proximity with the reedswitch is to cause the reed switch to close. In the embodimentillustrated, as long as the reed switch is closed, as when the warehousedoor is open, the NPN-type silicon RF high frequency transistor 62 isprevented from turning “on”, since in this condition of the situation,the door being open, it does not require protection from damage byforklift trucks. However, when the door closes, and the magnet on thedoor is removed from proximity with the reed switch, then the transistor62 turns “on”, and terminal pin 14 on the encoder designated generallyby the numeral 63 goes low, thus enabling the encoder to transmit a datasignal, the content of which is controlled by the selective actuation ofthe nine input switches designated generally by the numeral 64. We havefound an encoder of the type manufactured by Motorola and designatedMC145026 to be satisfactory for our purpose, since it will encode ninebits of information and serially transmit this information upon receiptof a transmit enable, i.e., active low, signal. The nine inputs may beencoded with trinary data (0, 1, and open), thus allowing 3.sup.9(19,683) different codes. It will thus be apparent that with this manycode options, the protective system of the invention can be “tailored”or “customized” for various customers to meet their specific operationalneeds, e.g., the transmitted radio signal is encoded with identifiabledata, and the radio receiver's data decoder decodes a stream of datareceived from the transmitter whereby different codes may be assigned todifferent forklift trucks whereby some forklift trucks are enabled toenter the restricted area while other forklift trucks are prevented fromentering the restricted area.

Resistors 66 and 67, and capacitor 68 set the time base for the encoder63. For the circuit illustrated, the data rate is approximately 420baud, or bits per second. The output from the encoder is channeledthrough resistor 69 to operational amplifier 71 which functions as abuffer for the data, and additionally controls the voltage onvoltage-variable capacitance diode 72, which receives the voltagethrough resistor 73. The voltage-variable capacitance diode 72 is of thetype designated MV2201 and manufactured by Motorola. The capacitance ofthe diode varies with the voltage across it, from 5.4 pF to 8.1 pF, witha nominal value of 6.8 pF.

This variance of capacitance in the diode 72 causes the resonantfrequency of the crystal 74 to shift slightly, allowing the data streamto frequency-modulate the oscillator 76. The crystal forms the basis forthe oscillator, which is tuned to the second harmonic (106 MHz) withinductance coil 77 and capacitor 78. The values of resistors 79, 81, and83 are tabulated below, as are the values of capacitors 84, 85, 86, 87and 88, and the value of the inductance coil 89. From the oscillator 76,the signal is channeled to the NPN-type silicon high-frequencytransistor 91 which functions as a radio frequency amplifier to multiplythe signal by three to 318 MHz, cooperating in this respect withinductance coil 92 and capacitor 93. The values of resistors 94, 96, and97, and capacitor 98 are tabulated below. From the amplifier 91, thesignal then passes through a bandpass filter formed by inductance coil101 and variable capacitor 102 before the signal reaches the finalamplifier 103 which is of the same type as amplifier 91 and is tunedwith inductance coil 104 and capacitor 106. From the amplifier 103, thesignal is channeled through a second bandpass filter formed by variablecapacitor 108 and inductance coil 109, from whence it passes through aresistive matching network made up of resistors 112, 113 and 114 to theoutput jack 116 of the antenna 9.

Receiver

Referring with greater specificity to the receiver schematic illustratedin FIGS. 4(A) and 4(B), power to the receiver is taken from the ignitionof the forklift truck through leads 121 and 122, the latter being aground lead. When the ignition is turned on to render the forklift truckoperative, the power to the receiver is also turned on, rendering thereceiver operative. As indicated, power enters the circuit through 0.5amp fuse 124, diode 123, through the voltage regulator 126 to the outputterminal 127. The diode 124 is a general purpose diode bearing thedesignation 1N4003 and manufactured by Motorola. The voltage regulatoris manufactured by National Semiconductor, and carries the designationLM7808. Capacitors 128 and 129 filter the voltage before and after theregulator 126.

The encoded signal transmitted by antenna 9 of the transmitter entersthe receiver through antenna 13 of the receiver and through antenna jack131. The signal passes through a bandpass filter designated generally bythe numeral 132 and formed specifically from inductance coils 133 and134, and variable capacitor 136 and fixed capacitors 137 and 138, thencethrough capacitor 139 to pre-amplifier 141, which functions as a tunedamplifier in cooperation with resistor 142, capacitors 143 and 144andinductance coil 146 to deliver the signal through capacitor 147 to themixer 148. Pre-amplifier 141 is of the MRF 904 type manufactured byMotorola, while the mixer 148 is an RCA MOSFET designated 3N211.

The mixer 148 also receives a signal from the local oscillatordesignated generally by the numeral 149, and through the tunedbuffer/amplifier designated generally by the numeral 151. The localoscillator 149 includes transistor amplifier 152and related circuitry,including crystal 153 having a resonant frequency of 51.2167 MHz,variable capacitor 154, resistors 156 157 and 158, and fixed capacitors159, 161, 162, 163, 164 and 166, and inductance coils 167 and 168.Transistor amplifier 152 is designated 2N2222 and is manufactured byMotorola. In this local oscillator circuit, inductance coil 167resonates with capacitor 164 to amplify the third harmonic of thecrystal 153 to a frequency of 153.65 MHz.

The tuned buffer/amplifier circuit 151 functions to double the localoscillator frequency of 153.65 MHz to 307.3 MHz, and feeds this doubledfrequency to the mixer 148. The tuned buffer/amplifier circuit 151includes a high frequency transistor 169 designated 2N5179 manufacturedby Motorola, resistor 171, fixed capacitor 172, variable capacitors 173and 174, and inductance coil 176.

Associated with the mixer 148 is a transformer 177 composed of inductivecoil 178 and capacitor 179. The transformer 177 resonates at 10.7 MHz,which is the differential between the frequency of the signal suppliedto the mixer by the pre-amplifier 141 and the local oscillator 149. Thetransformer 177 picks up the intermediate frequency and feeds it totransistor amplifier 181 for amplification into the ceramic filter 182.The transistor amplifier 181 works in conjunction with fixed capacitors183, 184, 186, and 187, and resistors 188, 189, 191, and 192 asillustrated. The transistor amplifier 181 is of the 2N2222 type similarto the transistor 152 utilized in the local oscillator. From the filter182, the signal passes through capacitor 193 to transistor amplifier194, also of the 2N2222-type similar to transistor amplifier 181. Thistransistor amplifier works in conjunction with resistors 196, 197, 198and 199, and fixed capacitors 201, 202 and 203 as shown. After passingthrough capacitor 203, the output signal from the transistor amplifier194 is again filtered by ceramic filter 204 and passes to thedemodulator chip 206. The demodulator chip 206 is manufactured by RCAand carries the trade designation CA3089, and constitutes a monolithicintegrated circuit which uses quadrature detection to demodulate the IFsignal into audio. As indicated in the drawing, the demodulator chip 206has two outputs at pins 6 and 13, a voltage level which variesproportionally with the signal strength, at pin 13, and the demodulatedaudio output at pin 6. Working in conjunction with the demodulator chip206 are resistors 207 and 208, fixed capacitors 209, 212, 213, and 214,fixed inductance coil 216 and variable inductance coil 217. The valuesfor these components are tabulated below.

The demodulated audio output from pin 6 is fed through resistor 218,capacitor 219 into operational amplifier 221, which is one of fouroperational amplifiers on the integrated circuit, which converts thedemodulated audio output into a datastream. Operational amplifier 221cooperates with resistors 222, 223, 224 and 226 to feed the signal intothe second operational amplifier 227 which is contained on the sameintegrated circuit as operational amplifier 221 and which functions togive the data stream sharper edges and re-inverts the signal to feed itto the data decoder device designated generally by the numeral 228. Asillustrated, a part of the assembly of the decoder device 228 includes aswitch designated generally by the numeral 229 and including a pluralityof switches which are pre-set to decode the data stream, the particulardecoder chip designated treating all nine bits of data received asaddress data. We have found that for our purpose, a decoder devicemanufactured by Motorola and sold under the trade designation MC 145028performs satisfactorily in the circuit. Resistors 230 and 231, andcapacitors 232 and 233 set the data rate for the decoder device 228 toapproximately 420 baud. Thus, if the data stream input into the decodermatches the address defined by the switch assembly 229, then the decoderdevice outputs a “high” voltage at pin 11. This voltage is appliedthrough resistor 234 to the transistor amplifier 236, which becomesconductive and charges capacitor 237, and tries to turn on transistoramplifiers 238 and 239, connected in parallel, the signal to thesetransistor amplifiers passing through resistors 241 and 242,respectively. It will of course be apparent from the circuit, that thetransistor amplifier 238 when in a conductive condition functions tosound the buzzer 243. Additionally, when the transistor amplifier 239 isin an on or conductive condition, it energizes the “kill” relay 244 tointerrupt the ignition circuit of the forklift truck and cause it tostop.

Whether or not transistor amplifiers 238 and 239 turn on or becomeconductive is controlled by transistor amplifiers 246 and 247,respectively, working in conjunction with resistors 248 and 249. Itshould be noted that transistor amplifiers 238239, 246 and 247 are allof the 2N2222-type similar to transistor amplifiers 236, 194, 181 and152.

As indicated above, the demodulator device 206 has two outputs, one ofthese being from pin 13 which outputs a voltage level which variesproportionally with the signal strength. The signal output from pin 13of demodulator 206 passes through an RC low-pass filter composed ofcapacitors 250 and 252, and resistors 253 and 254, before being input toone of two operational amplifiers 256 and 267 on the same integratedcircuit, the operation amplifier 256 functioning as a unity gain buffer.Resistors 258 and 259, and capacitor 261 function as a second RClow-pass filter before the voltage level is amplified by operationalamplifier 257. Operational amplifier 257 cooperates with resistors 262and 263 to feed the signal in parallel to operational amplifiers 264 and266 connected as shown, including 100K ohms potentiometer 267cooperatively associated with resistor 268 and operational amplifier264; and 100K ohms potentiometer 269, cooperatively related withresistor 271 associated with operational amplifier 266. Operationalamplifier 264 functions as a comparator to compare the signal strengthagainst the reference voltage set by potentiometer 267. When the signalstrength, or voltage, is greater than the reference voltage, the outputwill go low to turn off transistor amplifier 246, enabling transistoramplifier 238 to turn on the buzzer 243, provided of course, that thedecoder device 228 has received the correct data. Operational amplifier266, on the other hand, compares the signal strength against thereference voltage set by potentiometer 269. Again, when the signalstrength or voltage, is greater than the reference voltage, the outputof operational amplifier 266 will go low, to turn off transistoramplifier 247, enabling transistor amplifier 239 to turn on the relay tocut the ignition if the signal strength is greater than the referencevoltage, and again, if the correct data is received by the decoderdevice 228.

In the interest of clarity in the drawings, the values of the componentsutilized in the circuits have been omitted from the drawings, thecomponents being referred to by reference numbers. There follows intabulated form a listing of the components, indicated by referencenumber and indicating the nomenclature and, where appropriate, thepreferred value for each:

Transmitter

Reference No. Nomenclature Parameter 53 Fuse 0.5 Amp. 52 Transformer12.5 V CT. 54 Diode Rectifier Bridge 1N4003 56 Capacitor 470 uF 57Capacitor 0.1 uF 58 Voltage Regulator LM7812 59 Capacitor 470 uF 61Capacitor 0.1 uF 62 Transistor Amplifier 2N2222 63 Data Encoder MC14502664 Switch 66 Resistor 10K 67 Resistor 20K 68 Capacitor 0.0051 uF 69Resistor 10K 71 Operational Amplifier 72 Diode MV2201 73 Resistor 20K 74Crystal 76 Transistor Amplifier 2N2222 77 Coil 5.5 T 78 Capacitor 8 pF79 Resistor 9.1K 81 Resistor 620 ohms 83 Resistor 33 ohms 84 Capacitor0.001 uF 85 Capacitor 68 pF 86 Capacitor 91 pF 87 Capacitor 0.001 uF 88Capacitor 6 pF 89 Coil 0.22 uH 91 Amplifier MRF904 92 Coil 2.5 T 93Capacitor 2 pF 94 Resistor 9.1 K 96 Resistor 620 ohms 97 Resistor 33ohms 98 Capacitor 0.001 uF 99 Resistor 100 K 101 Coil 1.5 T @0.15″ Dia.102 Variable Capacitor 2-10 pF 103 Amplifier MRF904 104 Coil 2.5 T 105Capacitor 0.01 uF 106 Capacitor 1.0 pF 108 Variable Capacitor 2-10 pF109 Coil 1.5 T @0.15″ Dia. 112 Resistor 100 ohms 113 Resistor 100 ohms114 Resistor 75 ohms 116 Antenna jack.

Receiver

Reference Nomenclature Parameter 121 Input Lead +12 V 122 Ground Lead123 Fuse 0.5 Amp 124 Diode Rectifier 1N4003 126 Voltage Regulator LM7808127 Terminal +8 V 128 Capacitor 100 uF 129 Capacitor 100 uF 131 Antennajack 132 Bandpass Filter 133 Coil 2.5 T 134 Coil 2.5 T 136 VariableCapacitor 2-10 pF 137 Capacitor 5 pF 138 Capacitor 1.5 pF 139 Capacitor5 pF 141 Amplifier MRF904 142 Resistor 68K 143 Capacitor 1 pF 144Capacitor 0.001 uF 146 Coil 2.5 T 147 Capacitor 3 pF 148 3N211 MOSFETAmplifier To 200 MHz 149 Local Oscillator 153.65 MHz 151 TunedBuffer/Amplifier 307.3 MHz 152 Transistor Amplifier 2N2222 153 Crystal154 Variable Capacitor 10-40 pF 156 Resistor 9.6 K 157 Resistor 1 K 158Resistor 33 ohms 159 Capacitor 0.01 uF 161 Capacitor 68 pF 162 Capacitor91 pF 163 Capacitor 0.01 uF 164 Capacitor 3 pF 166 Capacitor 20 pF 167Coil 2.5 T 168 Coil 0.22 uH 169 Tuned Buffer/Amplifier 2N5179 171Resistor 82 K 172 Capacitor 0.001 uF 173 Variable Capacitor 2-10 pF 174Variable Capacitor 2-10 pF 176 Coil 1.5 T 177 Transformer 10.7 MHz 178Coil 179 Capacitor 181 Transistor Amplifier 2N2222 182 Ceramic Filter10.7 MHz 183 Capacitor 0.01 uF 184 Capacitor 0.01 uF 186 Capacitor 0.01uF 187 Capacitor 0.01 uF 188 Resistor 9.1 K 189 Resistor 910 ohms 191Resistor 330 ohms 192 Resistor 10 ohms 193 Capacitor 0.01 uF 194Transistor Amplifier 2N2222 196 Resistor 3.3 K 197 Resistor 330 ohms 198Resistor 330 ohms 199 Resistor 10 ohms 202 Capacitor 0.01 uF 203Capacitor 0.01 uF 204 Ceramic Filter 10.7 MHz 206 Demodulator ChipCA3089 207 Resistor 330 ohms 208 Resistor 8.2 K 209 Capacitor 0.01 uF212 Capacitor 0.01 uF 213 Capacitor 0.01 uF 214 Capacitor 100 pF 216Coil 0.22 uH 217 Variable Inductor Coil 218 Resistor 4.7 K 219 Capacitor0.1 uF 221 Operational Amplifier 222 Resistor 100 K 223 Resistor 4.7 K224 Resistor 4.7 K 226 Resistor 4.7 K 227 Operational Amplifier 228Decoder MC145028 229 Switch 230 Resistor 9.1 K 231 Resistor 200 K 232Capacitor 0.02 uF 233 Capacitor 0.02 uF 234 Resistor 1.0 K 236Transistor Amplifier 2N2222 237 Capacitor 100 uF 238 TransistorAmplifier 2N2222 239 Transistor Amplifier 2N2222 241 Resistor 10 K 242Resistor 10 K 243 Alarm Buzzer 244 Relay 246 Transistor Amplifier 2N2222247 Transistor Amplifier 2N2222 248 Resistor 10 K 249 Resistor 10 K 250Capacitor 0.001 uF 251 Capacitor 0.001 uF 252 Capacitor 0.01 uF 253Resistor 33 K 254 Resistor 33 K 256 Operational Amplifier 257Operational Amplifier 258 Resistor 47 K 259 Resistor 47 K 261 Capacitor0.01 uF 262 Resistor 220 K 263 Resistor 220 K 264 Operational Amplifier266 Operational Amplifier 267 Potentiometer 100 K 268 Resistor 100 K 269Potentiometer 100 K 271 Diode 1N914.

FIG. 8 is a block schematic diagram of an alternate preferred embodimentof the present invention for a security system 800. System 800 includesa first type of monitored area 805 (e.g., a warehouse or other storagefacility where forklift trucks operate) and a plurality of second typeof monitored areas 810 (e.g., the cargo areas of transportation systemslike trucks, railcars, and shipping containers as well as otherauxiliary storage rooms). System 800 includes an RFID subsystem 815 formonitoring monitored areas 805 and 810. One or more RFIDtransceiver/detector systems are used sufficient to monitor all theareas. Additionally in the preferred embodiment, RFID subsystem includesa query system for locating specific RFID tokens within the monitoredareas as well as a recording system for creating a history oftime-stamped RFID token entries and RFID token exits and othertransactions within the monitored areas.

Distributed throughout the preferred embodiment of system 800 areindicators 820. For ease of understanding, these are shown associatedwith each of a plurality of passageways from first monitored area 805 toeach of second monitored areas 810. These indicators 820 may be visualsignals (e.g., a type of traffic light having green (safe), yellow(caution), and red (stop) lights), audible (e.g.,horns/sirens/whistles), combinations, or other indication. Indicators820 may also be distributed within first monitored area 805 forproviding an indication within monitored subzones of first area 805.

One or more forklift trucks 825 or other vehicle operate with themonitored areas. Other vehicles that could pose a security/safety riskmay also operate within the monitored areas and would all be includedwithin the class of vehicles identified by truck 825. In someimplementations, each truck 825 is provided with a safety system 830. Insome instances, safety system 830 is an indicator similar to indicator820 to provide the operator with an indication of the status of thevarious areas/sub-zones they approach or are currently in. In otherinstances, in addition to or in lieu of, safety system 830 includes aninterlock system for disabling/preventing truck 825 from entering withincertain monitored areas/subzones under various conditions.

One or more people 835 may enter into the various areas. To reduce arisk of injury to these people 835, an operator of system 800 provideseach person 835 with an RFID token. In the preferred embodiment, RFIDtoken includes a hardhat with a first unique RFID tag 840 and a safetyvest with a second unique RFID tag 845. The operator of system 800associates tag 840 and tag 845 with a specific person 835. RFIDsubsystem 815 detects the tags, ensures that they match and form atoken, and determines which monitored area person 835 occupies at anygiven time. RFID subsystem activates one or more of indicators 820 and830 as appropriate based upon the location of person 835.

The following description of the operation of system 800 describes oneforklift truck 825 and one person 835 operating within one or moremonitored areas to simplify the discussion. It is understood that inother implementations there may be many forklift trucks, persons, andmonitored areas. In operation, an operator of truck 825 typicallyperforms loading tasks (e.g., loading and unloading) with respect to oneor more monitored areas or sub-zones thereof. The operator drivesquickly and the environment is often loud. When a forklift truck isloaded, visibility can be greatly impaired, particularly in the forwarddirection. Additionally, some of the monitored areas (particularly maybe true for the second monitored areas 810) lighting may be poor orabsent. It is common for person 825 to be required to be within some ofthe various monitored areas at the same time as the forklift trucks. Forexample, when second monitored area is a cargo area of a transportationtruck, person 835 may be the truck driver. Person 835 may enter intosecond monitored area to check on the loading/unloading status orotherwise check on the status of the contents. When person 835 entersinto a particular one of second monitored areas 810, indicator 820associated with that particular area will indicate caution or STOP/DONOT ENTER. Forklift truck 825 operator will not enter into theparticular area until the indicator is cleared by the person leaving themonitored area. In some cases, indicators 820 may not provide a highenough level of safety/security. This may be partially true because thevisibility of a visual-only indicator may be impaired at some times dueto a load on a forklift truck. The use of safety system 830 on eachforklift truck increases an ability of truck 825 operator knowing thatan approaching monitored area is unsafe. Depending upon conditions,truck 825 operator may proceed with caution, wait, take a differentroute, or exit the vehicle to make a direct visual inspection of theapproaching monitored area.

One reason that the preferred embodiment uses an RFID token consistingof a pair of associated RFID tags (one with a hardhat and one with asafety vest) is to help ensure that everyone within the areas use both.Additionally, the token help to ensure security of the area by helpingto detect when an unauthorized entrance is made into a monitored area.Entering into a monitored area with a goal of theft or subversion ofproduct quality (a concern of homeland security particularly for areasin which food or chemicals or the like is distributed) is harder usingthe RFID token system described. An unauthorized may not just find arandom hardhat and safety vest, but they must have a pair of tags thatare associated with each other. RFID subsystem 815 will still be able toprovide the detecting/indicating features based upon just one RFID tag,but detection of a mismatched pair of tags generates an action procedure(such as sending a message to a security personnel to investigate).

The recording component of RFID subsystem 815 may include cameras aswell. This helps to ensure that the activities in the monitored areasare appropriate and that procedures for the safety/security of thepersonnel and goods stored/passing through the monitored areas arefollowed.

In the description herein, numerous specific details are provided, suchas examples of components and/or methods, to provide a thoroughunderstanding of embodiments of the present invention. One skilled inthe relevant art will recognize, however, that an embodiment of theinvention can be practiced without one or more of the specific details,or with other apparatus, systems, assemblies, methods, components,materials, parts, and/or the like. In other instances, well-knownstructures, materials, or operations are not specifically shown ordescribed in detail to avoid obscuring aspects of embodiments of thepresent invention.

A “processor” or “process” includes any human, hardware and/or softwaresystem, mechanism or component that processes data, signals or otherinformation. A processor can include a system with a general-purposecentral processing unit, multiple processing units, dedicated circuitryfor achieving functionality, or other systems. Processing need not belimited to a geographic location, or have temporal limitations. Forexample, a processor can perform its functions in “real time,”“offline,” in a “batch mode,” etc. Portions of processing can beperformed at different times and at different locations, by different(or the same) processing systems.

Reference throughout this specification to “one embodiment”, “anembodiment”, or “a specific embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention and notnecessarily in all embodiments. Thus, respective appearances of thephrases “in one embodiment”, “in an embodiment”, or “in a specificembodiment” in various places throughout this specification are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics of any specificembodiment of the present invention may be combined in any suitablemanner with one or more other embodiments. It is to be understood thatother variations and modifications of the embodiments of the presentinvention described and illustrated herein are possible in light of theteachings herein and are to be considered as part of the spirit andscope of the present invention.

Embodiments of the invention may be implemented by using a programmedgeneral purpose digital computer, by using application specificintegrated circuits, programmable logic devices, field programmable gatearrays, optical, chemical, biological, quantum or nanoengineeredsystems, components and mechanisms may be used. In general, thefunctions of the present invention can be achieved by any means as isknown in the art. Distributed, or networked systems, components andcircuits can be used. Communication, or transfer, of data may be wired,wireless, or by any other mechanism.

It will also be appreciated that one or more of the elements depicted inthe drawings/figures may also be implemented in a more separated orintegrated manner, or even removed or rendered as inoperable in certaincases, as is useful in accordance with a particular application. It isalso within the spirit and scope of the present invention to implement aprogram or code that can be stored in a machine-readable medium topermit a computer to perform any of the methods described above.

Additionally, any signal arrows in the drawings/Figures should beconsidered only as exemplary, and not limiting, unless otherwisespecifically noted. Furthermore, the term “or” as used herein isgenerally intended to mean “and/or” unless otherwise indicated.Combinations of components or steps will also be considered as beingnoted, where terminology is foreseen as rendering the ability toseparate or combine is unclear.

As used in the description herein and throughout the claims that follow,“a”, “an”, and “the” includes plural references unless the contextclearly dictates otherwise. Also, as used in the description herein andthroughout the claims that follow, the meaning of “in” includes “in” and“on” unless the context clearly dictates otherwise.

The foregoing description of illustrated embodiments of the presentinvention, including what is described in the Abstract, is not intendedto be exhaustive or to limit the invention to the precise formsdisclosed herein. While specific embodiments of, and examples for, theinvention are described herein for illustrative purposes only, variousequivalent modifications are possible within the spirit and scope of thepresent invention, as those skilled in the relevant art will recognizeand appreciate. As indicated, these modifications may be made to thepresent invention in light of the foregoing description of illustratedembodiments of the present invention and are to be included within thespirit and scope of the present invention.

Thus, while the present invention has been described herein withreference to particular embodiments thereof, a latitude of modification,various changes and substitutions are intended in the foregoingdisclosures, and it will be appreciated that in some instances somefeatures of embodiments of the invention will be employed without acorresponding use of other features without departing from the scope andspirit of the invention as set forth. Therefore, many modifications maybe made to adapt a particular situation or material to the essentialscope and spirit of the present invention. It is intended that theinvention not be limited to the particular terms used in followingclaims and/or to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include any and all embodiments and equivalents falling within thescope of the appended claims. Thus, the scope of the invention is to bedetermined solely by the appended claims.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A security system, comprising: an RFIDsubsystem including one or more RFID transceiver/detector systemsdetecting an entry of an RFID token within a monitored area wherein saidRFID subsystem is fixed to a first immobile structure within saidmonitored area and wherein said RFID subsystem wirelessly transmits anactivating signal when detecting said entry of said RFID token withinthe monitored area; an RFID token associated with a person accessingsaid monitored area; and an indicator system, including an entryindicator coupled to a second immobile structure within said monitoredarea, said entry indicator having a wireless receiver responsive to saidactivating signal, providing an indication when said person enters intosaid monitored area by detecting said associated RFID token.
 2. Thesystem of claim 1 wherein said indicator system includes a safety systemcoupled to a forklift truck operable within said monitored area, saidsafety system including an interlock system and a wireless receiverresponsive to said activating signal, coupled to said forklift truck,disabling said forklift truck from entering into said monitored areawhen said person is within said monitored area.
 3. The system of claim 1wherein said entry indicator includes a visual indicator that providesvisual cues when said person enters into said monitored area.
 4. Thesystem of claim 3 wherein said indicator system includes a set of statuslights for indicating a clear mode, a caution mode, and a warning mode.5. The system of claim 1 wherein said indicator system includes aportable indicator system associated with a forklift truck operatingwithin said monitored area, said portable indicator system having awireless receiver responsive to said activating signal.
 6. The system ofclaim 1 wherein said entry indicator includes an audible indicator thatprovides audible cues when said person enters into said monitored area.7. The system of claim 1 wherein said RFID token is associated with anarticle of clothing worn by said person.
 8. The system of claim 7wherein said RFID token is provided in a safety vest issued to saidperson.
 9. The system of claim 7 wherein said RFID token is provided ina hardhat issued to said person.
 10. The system of claim 1 wherein saidRFID token includes a first RFID tag associated with a first article ofclothing and a second RFID tag associated with a second article ofclothing, said RFID tags having a specified association.
 11. The systemof claim 10 wherein said RFID subsystem monitors for said first andsecond RFID tags and said specified association, said RFID subsystemproviding an alert when said specified association does not exist. 12.The system of claim 11 wherein a first one of said associated RFID tagsis associated with a hardhat and wherein a second one of said associatedRFID tags is associated with a safety vest.
 13. The system of claim 1wherein a vehicle operates within said monitored area and wherein anoperator of said vehicle is associated with a second RFID token andwherein said RFID subsystem tracks said second RFID token within saidmonitored area.
 14. The system of claim 1 further comprising a recordingsystem coupled to said RFID subsystem storing a history of times ofentry and exit of said person with respect to said monitored area.
 15. Asystem, comprising: an RFID subsystem including one or more RFIDtransceiver/detector systems detecting an entry of one or more RFIDtokens within one or more monitored areas wherein said RFID subsystem isfixed to a first immobile structure within said one or more monitoredareas and wherein said RFID subsystem wirelessly transmits an activatingsignal when detecting said entry of said RFID token within the monitoredarea; an RFID token associated with each person accessing any of saidmonitored areas; and an indicator system, including an entry indicatorcoupled to a second immobile structure within said monitored area, saidentry indicator having a wireless receiver responsive to said activatingsignal, providing an indication when any person enters into one of saidmonitored areas responsive to a detection of any associated RFID token.16. A method, the method comprising: (a) detecting an entry of one ormore RFID tokens within one or more monitored areas using an RFIDsubsystem by use of an RFID subsystem fixed to a first immobilestructure within said one or more monitored areas; (b) transmittingwirelessly an activating signal from said RFID subsystem when detectingsaid entry of said RFID token within the monitored area; and (c)indicating, using an entry indicator coupled to a second immobilestructure within said monitored area, to a driver of a vehicle enteringinto said one or more monitored areas responsive to said activatingsignal wirelessly received from said RFID subsystem, when one or moreRFID tokens have been detected within said one or more monitored areas.17. The method of claim 16 wherein said vehicle includes a safety systemwith a wireless receiver and wherein said indicating process includesdisabling said vehicle, responsive to said activating signal, fromentering said one or more monitored areas.
 18. The method of claim 16wherein said RFID token includes a pair of associated RFID tags.
 19. Thesystem of claim 1 further comprising a location system that locates aspecific RFID token within said monitored area.
 20. The system of claim1 wherein said monitored area includes a first region and wherein saidindicator system includes a first indicator fixed and immobile andassociated with said first region, wherein said indication includes aresponse by said first indicator; and wherein said response by saidfirst indicator is responsive to a status of said person within saidfirst region.
 21. The system of claim 20 wherein said monitored areafurther includes a second region and wherein said indicator systemincludes a second indicator fixed and immobile and associated with saidsecond region, wherein said indication includes a response by saidsecond indicator; and wherein said response by said second indicator isresponsive to a status of said person within said second region.
 22. Asystem, comprising: an RFID subsystem for detecting entry of an RFID tagwithin a monitored area; an RFID token associated with a personaccessing said monitored area; and an indicator system for providing anindication when said person enters into said monitored area; whereinsaid RFID token includes a pair of associated RFID tags.
 23. A system,comprising: an RFID subsystem detecting entry of an RFID tag within afirst monitored area wherein said RFID subsystem includes one or moretransceivers/detectors, wherein said first monitored area includes oneor more immobile structures, and wherein at least one particulartransceiver/detector of said one or more transceivers/detectors arefixed to one particular immobile structure of said one or more immobilestructures; one or more RFID tokens, an RFID token associated with eachperson entering into said first monitored area; and an indicator systemproviding an indication when a person enters into said first monitoredarea.
 24. The system of claim 23 wherein said first monitored areaincludes a storage facility wherein one or more vehicles operate andwherein said particular immobile structure includes a wall within saidstorage facility.
 25. The system of claim 24 wherein said firstmonitored area consists essentially of a stationary type of monitoredarea, the system further comprising a second monitored area consistingessentially of a mobile type of monitored area coupled to said firstmonitored area through a portal; wherein said one or more RFID tokensare associated with said one or more persons entering into said secondmonitored area; wherein said RFID subsystem detects entry of any RFIDtag of said one or more RFID tags into said second monitored area; andwherein said indicator system provides said indication responsive tosaid person entering into said second monitored area.
 26. The system ofclaim 25 wherein a particular one RFID token is associated with aparticular person, the system further comprising a recording systemcoupled to said RFID subsystem storing automatically a history of timesof entry and exit of said particular person with respect to saidmonitored areas and responsive to said RFID token.
 27. The system ofclaim 25 wherein a particular RFID token is associated with eachparticular person entering into one of said monitored areas, the systemfurther comprising a locating system coupled to said RFID subsystemlocating automatically each particular person with respect to saidmonitored areas and responsive to said associated RFID tokens.
 28. Thesystem of claim 25 wherein said indicator system includes an indicatorassociated with said portal.
 29. The system of claim 28 wherein saidvehicles and said persons comprise mobile elements within said monitoredareas; wherein said portal includes a portal control physically limitingwhether a mobile element may move from said first monitored area to saidsecond monitored area with said portal control including an open modewhen movement from said first monitored area to said second monitoredarea is possible and a closed mode when movement from said firstmonitored area to said second monitored area is not possible; andwherein said indicator is additionally responsive to said mode of saidportal with said indicator providing said indication only when both saidportal is in said open mode and when said person is within said secondmonitored area.
 30. The system of claim 24 wherein said first monitoredarea consists essentially of a stationary type of monitored area andwherein said wall includes a portal accessing a second monitored area.31. The system of claim 30 wherein said one or more vehicles may travelthrough said portal; wherein said portal includes a door having an openmode and a closed mode; wherein said second monitored area consistsessentially of a mobile type of monitored area; wherein a side of saidportal included in said second monitored area includes a hazard to anyone of said vehicles traveling through said portal in said open modewhen said second monitored area is absent; and wherein said indicatorsystem provides said indication whenever said door is in said open modeand said second monitored area is absent from said side of said portal.32. The system of claim 31 wherein said RFID subsystem includes adistance feature and wherein said indicator system is responsive to saiddistance feature to actuate said indicator whenever a particular onevehicle of said one or more vehicles approaches said portal within saidfirst further distance.
 33. The system of claim 32 wherein said distancefeature distinguishes between a first further distance and a secondcloser distance and wherein said indicator system is responsive to saidfirst further distance to actuate said indicator, the system furthercomprising a lockout system, responsive to said second closer distanceand coupled to both said RFID subsystem and to said particular onevehicle, disabling said particular one vehicle from being driven throughsaid portal when said indication is active.
 34. The system of claim 30wherein said one or more vehicles may travel through said portal;wherein said portal includes a door having an open mode and a closedmode; wherein said second monitored area consists essentially of amobile type of monitored area; wherein said one or more RFID tokens areassociated with said one or more persons entering into said secondmonitored area; wherein said RFID subsystem detects entry of any RFIDtag of said one or more RFID tags into said second monitored area; andwherein said indicator system provides said indication whenever saiddoor is in said open mode and said second monitored area is present andsaid second monitored area is occupied by a person.